Added manga data and pipeline.

MangaReader.Core/Data/MangaSource.cs

@@ -0,0 +1,12 @@
+namespace MangaReader.Core.Data;
+
+public class MangaSource
+{
+    public int MangaId { get; set; }
+    public required Manga Manga { get; set; }
+
+    public int SourceId { get; set; }
+    public required Source Source { get; set; }
+
+    public required string Url { get; set; }
+}